Melt extrudable cold water-soluble films

ABSTRACT

Films, 0.5-10 mils thick, which are rapidly and completely soluble in cold water, and which are suitable for use as packaging film in automatic packaging equipment, can be prepared by conventional melt extrusion processes when prepared from a novel composition consisting essentially of 5-20 parts by weight of a polyethylene glycol (having an average molecular weight in the range between 325 and 550) in 100 parts by weight of a partially hydrolyzed low molecular weight polyvinyl alcohol.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of application Ser. No. 739,280, filed Nov. 5,1976, now abandoned which in turn is a continuation-in-part of myapplication Ser. No. 525,446, filed Nov. 20, 1974, now abandoned whichin turn is a continuation-in-part of may application Ser. No. 430,554,filed Jan. 3, 1974, now abandoned.

BACKGROUND OF THE INVENTION

Many commonly used chemicals are produced and sold in pulverulent form,but are then slurried, dispersed, or dissolved in water when used by theconsumer. Examples of these materials are pesticides (specificallyinsecticides, herbicides, nematicides, and fungicides, and the like)which are applied as a water spray, cleaning products (such as laundrydetergents, bleaches, and caustic cleansers) which are dissolved in washwater, process chemicals (such as carbon black and activated charcoal)which can be slurried in water, and pigments and dyes which aredissolved or dispersed.

There are several problems associated with the use of these types ofproducts. The first of these problems is exposure of the user and hisimmediate surroundings to the chemical. Opening a package of finelyground material, measuring an amount of the material, and transferringthe measured amount from the package to the equipment where the materialis contacted with water can generate airborne dust which contacts theuser and contaminates the area. A pesticide dust could be irritating tothe eyes and mucous membranes of the nose and throat of the user. Aherbicide dust could damage plants in the area where the packages areopened. Dusts of pigments or activated charcoal present severe clean-upproblems.

The second problem in using common pulverulent chemicals is accuracy ofmeasurement. Clearly, overcharging of expensive materials is costly. Useof a weak solution of a herbicide will not properly control theundesired plant species. Use of too strong a solution of the samematerial may damage some desired plants as well as the undesired weeds.It is frequently extremely difficult to accurately measure materialswhich have become compacted and/or lumpy and to transfer powderymaterials in areas exposed to wind.

Finally, after the chemical has been used, the user is faced with theproblem of disposing of the package in which the chemical was delivered.It may contain residual amounts of a material which is a pollutionproblem, potentially hazardous to humans, harmful to plants and animals,or merely unpleasant and unsightly.

Currently available water-soluble films and packages possess one or moreof a variety of deficiencies such as the following:

(a) Many films which are characterized as water soluble dissolve slowlyor dissolve incompletely in cold water, resulting in the formation ofgel-like particles. These particles tend to deposit on vessel walls,piping, pumps, and valves and restrict or prevent flow through screensand nozzles. The melt-extrudable films of this invention are rapidly andcompletely soluble in water at temperatures as low as 4° C. and do notform gel-like particles of undissolved or partially dissolved polymer.

(b) Many of the compositions utilized in the preparation of such filmspossess physical properties which are such that large, expensive, highlyenergy consuming and technologically complex process equipment for filmmanufacture, e.g., solvent-casting (or doctor knife or bandcasting) isrequired. A typical solvent-casting process involves dissolving thecomposition in a suitable solvent (e.g., water), spraying or pouring andspreading the composition on a moving belt, drying the composition,generally, by evaporation of the excess solvent, stripping the driedfilm from the moving belt and then cutting or shaping into the desiredform. The technological complexity of such a process is self-evident.Also that process equipment performing so many steps would be large andexpensive is equally clear. However, in consideration of current costsand availability of energy, perhaps even more significant is that aprocess step involving drying by evaporation of large quantities ofwater will require the expenditure of enormous amounts of energy.

Preferable to such preparation methods is melt extrusion. Melt-extrusionprocess equipment compared to the equipment used in water casting, isextremely small, inexpensive, technologically simple, and consumes verylittle energy.

(c) Many water-soluble films of the prior art possess physicalproperties which make the film unsuitable for use in packagingquantities of pulverulent materials in the range of one half to tenpounds (e.g. yield strength, tear resistance, toughness, flexibility).Such films are also unsuitable for use in automatic packaging machinery.

(d) The constituents of many of the water-soluble packaging filmscurrently available are numerous, difficult to obtain, and/or expensive.

(e) Examples of prior art teachings include Japanese Pat. No. 28,588/69,U.S. Pat. No. 3,374,195, and its divisional U.S. Pat. No. 3,413,229, andUnited Kingdom Pat. No. 1,330,745.

The Japanese Patent teaches that a melt-extrudable water-soluble filmcan be made from a polyvinyl alcohol having viscosity of 18 cps±2 andany of many polyols. Certain draw and melt temperature restrictions aretaught. These films include many which are not rapidly water soluble,many which exude upon melt extruding, and many which are not suitable aswater-soluble packaging film.

U.S. Pat. No. 3,374,195 teaches an aqueous cast film which is hot orcold water soluble. The film consists of PVA and a combination of twoplasticizers, which is a polyethylene glycol of mw 200-600 andhydroxypropyl glycerine. This patent does not teach that the compositionis melt extrudable and does teach hydroxypropyl glycerine as a necessarycoplasticizer.

The United Kingdom Patent teaches an aqueous cast film which is hot orcold water soluble. The film consists of PVA and a combination ofpolyvinyl pyrrolidone and an optional plasticizer. This patent does notteach that the composition is melt extrudable and does teach polyvinylpyrrolidone as a necessary constituent.

SUMMARY OF THE INVENTION

Compositions consisting essentially of 5-20 parts by weight of apolyethylene glycol with an average molecular weight of about 325-550(based upon measurement of the hydroxyl content thereof obtained byesterification of the glycol with phthalic anhydride/pyridine--page 28of "Carbowax® Polyethylene Glycols", Bulletin F-4772G, 1/72-IOM, ofUnion Carbide Corporation) in 100 parts by weight of a polyvinyl alcoholwhich is 85-90 mol% hydrolyzed (dry basis, determined by saponification,e.g. with KOH) and has a viscosity of 3-10 cps as measured on a 4%aqueous solution at 20° C., have been found suitable for preparing byconventional melt extrusion process films 0.5-10 mils (1 mil=0.0254 mm.)thick of the same composition, which are rapidly and completely solublein cold water, and which are suitable for use as packaging film inautomatic packaging equipment.

Suitable compositions can be made from commercially available polyvinylalcohol and polyethylene glycol which are each comparativelyinexpensive.

The films can be used to package pulverulent materials. The film packagecontaining the pulverulent material can be directly charged to water,thus eliminating the problems of user contact, exact measuring, andcontainer disposal.

The films also pass the Standard Tests taught in the specification.

DETAILED DESCRIPTION OF THE INVENTION

As used herein the term "film" is intended to mean single layerstructures, and excludes laminates. Only low molecular weight (viscosityof about 3-10 cps as measured on a 4% aqueous solution at 20° C. by theHoeppler falling ball method ASTM-D 1343-56 Part 8, 1958, page 486)polyvinyl alcohol is suitable. Medium or high molecular weight polyvinylalcohols result in films which are not practical to extrude, and/or failat least one of the Standard Tests. In addition, the polyvinyl alcoholmust be only partially hydrolyzed to a degree of 85-90 mol%. Thepolyvinyl alcohol can be prepared from polyvinyl acetate by hydrolysisin which acetate groups are replaced by hydroxyl groups to the desiredpercentage.

Concerning the glycols, only polyethylene glycol having an averagemolecular weight range of about 325-550 is suitable. Using polyethyleneglycols of lower or higher molecular weights, such as the commerciallyavailable PEG 300 and PEG 600, results in compositions which fail one ormore of the Standard Tests. Similarly, using glycols such as ethyleneglycol, diethylene glycol, triethylene glycol, polypropylene glycol, andglycerol also result in unsatisfactory compositions.

In characterizing the polyethylene glycol to be used in the compositionsand films of the present invention, an alternative means ofidentification is by the average degree of polymerization. That is, incharacterizing a polyethylene glycol of the formula

    HO(CH.sub.2 CH.sub.2 O).sub.n H

n is the degree of polymerization. Whether the polyethylene glycol ischaracterized by average molecular weight or by degree ofpolymerization, when a particular molecular weight or degree ofpolymerization is specified, it is meant to include materials which arepredominantly, but not necessarily entirely, of the specified averagemolecular weight or the specified degree of polymerization. For example,small quantities of lower and higher molecular weight materials can bepresent. A typical molecular weight distribution of polyethylene glycolsis shown for Union Carbide's Carbowax® 400 in the bulletin, "CarbowaxPolyethylene Glycols," page 22, F-4772G, 1/72-10 M. Polyethylene glycolshaving average degrees of polymerization of 7-12 are suitable for thecompositions of the present invention.

Proper proportioning of the two components is imperative. Use of lessthan 5 parts by weight of the polyethylene glycol per 100 parts of thepartially hydrolyzed polyvinyl alcohol results in a composition which isno longer rapidly cold water-soluble, which tends to be slow in meltextrusion, and which tends to be brittle as a film. Use of more than 20parts by weight of the polyethylene glycol per 100 parts of thepartially hydrolyzed polyvinyl alcohol results in a composition whichhas an adequate extrudability rate, but which exhibits an unacceptabledegree of exudation, i.e., the polyethylene glycol is at least partiallyrejected by the polyvinyl alcohol, resulting in a slimy coating of thefilm.

These films can be prepared at commercial rates using conventional meltextrusion apparatus such as is commonly used in the preparation ofpolyethylene, polypropylene, or polyvinyl chloride films. The novelcomposition of the present invention in the form of powder, granules, orpellets is melted, extruded through a slit or annulus, quenched by airand then drawn down and/or blown to form a thin film. Such stretchingcan impart orientation to the film.

PREFERRED EMBODIMENTS

The most preferred plasticizers because of their commercial availabilityare polyethylene glycols having an average molecular weight of 380 to420, for example, Carbowax® 400--Union Carbide, New York, New York.Other polyethylene glycols believed to be equivalent to Carbowax® 400are Poly G® 400--Olin Chemicals, Stamford, Connecticut, and Gafanol®E400--GAF Corporation, New York, New York.

Commercially available polyvinyl alcohols, having a viscosity in therange between about 3-10 cps and a degree of hydrolysis of about 85 to90 mol%, are suitable for this invention. These include Elvanol® 51-05(viscosity 4-6 cps, 87.7-89.7 mol% hydrolyzed) Du Pont, Gohsenol® GL-05(viscosity 4.8-5.8 cps, 87-89 mol% hydrolyzed) Nippon Gohsei, andGelvatol® 20-30 (viscosity 4-6 cps, 85.5-88.7 mol% hydrolyzed) Monsanto.

The preferred relative amounts of the two primary constituents is from12-17 parts by weight (pbw) of the polyethylene glycol in 100 pbw of thepolyvinyl alcohol, with the most preferred embodiment being 15 pbw ofthe PEG to 100 pbw of the PVA.

Small quantities (≦5 pbw based on 100 pbw PVA; preferably 0.1-2 and mostpreferred 0.1-1 pbw) of adjuvants commonly used in cellulose, vinyl, orpolyolefin films such as antioxidants, release agents, antiblock agents,and slip agents may be incorporated either before or after extrusion,providing the water solubility or other primary properties of theresulting film are not appreciably impaired. For example, the web couldbe dusted with talc during windup prior to storage or packaging. Thefollowing materials are preferably included in the composition prior toextrusion. Inorganic fillers such as clays, silicas (e.g., Cab-o-sil®L-5 (0.05 microns) or M-5 (0.012 microns) Cabot Corp., Boston, Mass.),alumina, silicates such sodium silicate, lithium polysilicate(Polysilicate® 85--E. I. du Pont de Nemours and Company, Wilmington,Delaware) or hydrated sodium silico-aluminates (e.g. Zeolex® 23A, J. M.Huber Corp., New York, New York) can be used. Useful organic materialsinclude among others (1) long chain fatty acids, alcohols, amides, orsalts (e.g., stearic acid, stearyl alcohol, erucamide, magnesium orcalcium stearate, (2) waxes, (3) partially oxidized low molecular weightpolyethylene (e.g., XL-223--American Hoechst), and (4) silicones (e.g.,dimethylsilicones).

In addition, small quantities of water-soluble polymers which arepartially compatible with the polyvinyl alcohols of the presentinvention can be advantageously included as coplasticizers, provided thepartially compatible polymer constitutes no more than 2 pbw based on 100pbw PVA. Examples of such partially compatible polymers includepolyethers of the formula --[CH₂ CH₂ O]_(n) -- with a molecular weightof at least 600 which are sometimes referred to as polyethylene glycolsand sometimes as polyethylene oxides, polypropylene glycols orpolypropylene oxide/ethylene oxide copolymers of at least 400 molecularweight. Polyethylene oxides of molecular weight 500,000-1,000,000 aremost preferred. Molecular weights for all such polyethylene glycols,polyethylene oxides and said copolymers are determined as describedabove.

Further, atmospheric moisture acts as a coplasticizer which toughens thefilm. In the process for preparing the films of the present invention bymelt extrusion, the operting temperature of the equipment result inthere being little or no water present in the film as it is firstformed. However, as the film leaves the extrusion apparatus, it contactsand begins to equilibrate with the ambient atmosphere commonlycontaining moisture of from 25-70% relative humidity. The preferred drybasis moisture content of the film before slitting is 4-5%; 5-7% ispreferred for the finished film for packaging. The preferred relativehumidity range for automatic packaging is from 25-65% with 35-55% beingmost preferred.

The films of this invention are preferably prepared by blow extrusion,which is particularly useful since biaxial orientation can be achievedduring this stretching process. Orientation toughens the film (e.g., inimpact strength and tear strength).

The films of the present invention are rapidly (less than one minute permil thickness) and completely soluble in cold water, i.e., water as coldas 40° F. (4° C.), such as would be available for large scaleagricultural use in Spring or Fall. Of course, in warmer water, the rateof dissolution increases. These films are most useful in terms ofmachinability in automatic packaging equipment and handlability offilled packages. The extruded films are particularly useful forpackaging pulverulents on conventional packaging lines, e.g., verticalmake-and-fill machines where heat-sealed pillow packs are produced. pThe cold water-soluble packaging films of this invention areparticularly useful for packaging pulverulent, dusty, noxious,irritating, and/or toxic materials which must be dispersed, slurried,suspended or dissolved in water or mixed solvents, one of which iswater. For this reason the film is especially suited for packagingagricultural chemicals. The films of the present invention can also beused in the packaging of liquid substances, such as liquid agriculturalformulations which are to be dispersed in water and which are based onwater-immiscible and polyethylene glycol a hyphen immiscible oils andhydrocarbons such as cyclohexane, mineral oil, and kerosene. Examples ofmaterials which are usefully packaged in premeasured portions inpackages made of the films of the present invention are pesticides (suchas insecticides, herbicides, nematicides, and fungicides), cleaningproducts (such as laundry detergents, bleaches, and caustic products),process chemicals (such as catalysts for polymerizations, carbon black,activated charcoal, pigments, and dyes), foodstuffs, and food additives.Other uses involve preparing premeasured portions of incompatiblematerials such as flour and oil; benomyl and maneb fungicides; and thelike in separate water-soluble film packages and overwrapping theseseparate packages in a single moistureproof packaging material. Whenused, the separate water-soluble packages containing the premeasuredportions of additive or chemical are added simultaneously to the liquidin suitable mixing equipment, thus preventing premature reaction ormixture and eliminating sources of measuring errors.

In order to protect the water-soluble package during storage, shipping,and handling, a moistureproof overwrap must be provided to preventdamage from atmospheric moisture such as high humidity, rain, and dewand from accidental contact with water by splashing or from wet hands.This moistureproof overwrap can be provided for either individualpackages or groups of packages, whichever appears to be most desirablefor the individual case. Moistureproofed cartons may be used. Of course,once the overwrap is removed, the soluble packages must be protectedfrom water contact or must be used promptly.

Suitable materials for the overwrap are the polyolefin films such aspolyethylene or polypropylene, Kraft paper moistureproofed withpolyethylene, moistureproof cellophane, glassine, metal foils,polyester, polyvinyl chloride, polyvinylidene chloride, and combinationsof these materials as in laminates. The choice of the overwrap would bedictated by costs and strengths required.

Thus, the compositions of this invention have the following combinationof properties: (1) easily fabricated by conventional melt extrusionprocesses into a film without the necessity of water and withoutaccompanying exusion; (2) the melt-extruded films (a) can be orientedduring extrusion to provide varying degrees of toughness, (b) arerapidly and completely cold water-soluble, and (c) are suitable for usein automatic packaging equipment.

The following Examples and Test Procedures further illustrate thepresent invention. All parts and percentages are by weight unlessspecified otherwise (pbw=parts by weight).

STANDARD TESTS I. Composition Constituent Compatibility

This is a test for exudation of the plasticizer from a film underambient conditions (i.e., 25° C., 25-70% relative humidity).

This test is conveniently performed on a film which has been meltextruded or has been solution cast as follows:

Approximately 30 grams of an aqueous stock solution (10-40%) of thedesired polyvinyl alcohol is stirred with the desired amount of neatplasticizer at room temperature with a high speed disc stirrer until themixture is visually homogeneous. Brief steam heating can be used to aidthe mixing. The resulting casting solution is poured onto a 1.91 cm.thick Lucite® plate and drawn down with a doctor knife having aclearance such that a 1-2 mil film can be stripped from the platefollowing overnight drying at ambient conditions.

Exudation exists to an undesirable level where a layer of plasticizer isevident by visual inspection of a film upon wiping a cotton swab acrossits surface.

II. Cold Water Solubility Rate

Each of the following tests is performed on film which has beenpre-equilibrated to 25-70% relative humidity for approximately 24 hours.

A. Spray Tank Cold Water Solubility Rate

In general, this test simulates tank conditions in the field. A packageof pesticide is dropped into cold water with mild agitation and thepesticide is dispersed. The resulting aqueous dispersion (or solution)is pumped through a fine screen. The screen is then quickly sprayed witha fine mist of a developing dye solution and is inspected for residualgels or pieces of film.

In particular, a 18.9 liter capacity steel spray tank (30.5 cm. diameterby 55.9 cm. high) is insulated and is filled with tap water, and cooledto 4° C. The water is circulated at a rate of about one gallon/minutethrough a valve at the bottom of the tank, through a centrifugal pump(Eastern Industries, Model D6, Type 215, 1550 RPM, 1-3 amp., 1/30 HP.).and back into the top of the tank. A heat-sealed "pillow pack" preparedfrom the film under test and containing a pulverulent pesticide isdropped into the tank. A timer is started immediately, and the "breaktime" (which occurs when the water first enters the pillow pack andcontacts the pesticide) and the "release time" (which occurs when thepackage sinks or when the pesticide begins to disperse and separate fromthe remains of the package--generally the pesticide drops away from thefloating package) are noted.

A steel paddle stirrer (7.62 cm. wide×1.91 cm. high×0.32 cm. thick) isdriven at 300 RPM. Each minute, a sample of the stream entering the tankis check for gel by passing it through a 50 mesh screen (opening 0.297mm., wire diameter 0.215 mm.) suspended just above the tank. As soon asthis inspection reveals no further gel, the time is noted. This time isconsidered to be a valid indication of complete dissolution if, uponimmediately dumping the entire tank contents through the screen anddeveloping the screen by spraying wtth a saturated aqueous solution ofFD&C Blue No. 1, no gel is found. The absence of gel when the entireoperation is completed within 10 minutes is considered satisfactory.

B. Film Disc Cold Water Solubility Rate

This is a quick laboratory test which simulates the Spray Tank ColdWater Solubility Rate test described in detail above. The gauge of a3.18 cm. diameter disc of film 1-2 mils in thickness is measured to thenearest 0.1 mil with a micrometer. A rubber gasket, formed by punching a2.54 cm. diameter hole in a rubber disc 3.49 cm. in diameter and 0.16cm. thick, is placed on the film disc and two flat metal rings, thesmaller having a 2.54 cm. diameter hole, are used as a frame to clampthe disc tightly. The frame with film mounted therein is placed on asmall tripod and a lead shot of 2.00-2.38 mm. diameter is placed on thefilm disc. This entire rig is lowered into a one liter beaker (thetripod is 1/2 as high as the beaker) containing 900 ml. of tap water at4° C., and a timer is started immediately. The "drop time" (when theshot breaks through the film disc) is noted, and a 5.08 cm. magneticstirring bar is started and maintained at 75 RPM. As soon as visualinspection reveals no further gel or pieces of film, the time is noted.This time is considered to be a valid indication of complete dissolutionif, upon immediately pouring the solution through a screen anddeveloping as in the Spray Tank Test, no gel is found. The finalsolubility rate is reported as minutes/mil for total dissolution. Valuesless than or equal to one minute/mil are considered satisfactory.

III Melt Extrudability

A. The test instrument used in this test is a Plastometer (Model C, F.F. Slocomb Corp., Wilmington, Delaware) fitted with an orifice 0.8 cm.long and 0.20 cm. in diameter. The piston and weight are 100 and 4900grams, respectively.

One-half to one gram of the film composition conveniently in the form offilm strips (aqueous cast film from Test I) are loaded into the barrelwhich is preheated to 210° C., and the piston is pushed down by hand tocompact the film. Granular or pelletized compositions may also be used,but longer preheat times are required. With a Teflon® plug set againstthe orifice, the film composition under test is allowed to preheat forabout 7 minutes. The plug is removed and the weight is placed on thepiston. As a rod of molten polymer begins to extrude, it is cut off witha spatula, and a stopwatch is started simultaneously therewith.

The newly issuing rod is collected on a polished stainless steel platepositioned 7.62 cm. below the orifice until the rate visually slows oruntil four minutes elapses. The rod is cut and the watch stopped. Theextrudate is weighed and an "extrudability index" is calculated as gramsper 10 minutes.

During collection, exudation or evolution of off-gas is noted. Theextrudate is examined for exudation or melt fracture on its surface,clarity, color, toughness, and bubbles. Exudation or volatization canalso be evidenced by the appearance of a fog of plasticizer on the steelplate.

Compositions exhibiting an extrudability index greater than 1, and whichare clear, smooth, tough (as evidenced by bending the rod upon itselfwithout breakage), non-bubbled and non-exuded are consideredsatisfactory.

B. Self-compatability of the melt extruded composition is determined bystoring for 48 hours at 70% relative humidity. Sweaty or wet surfaces onthe extrudate are considered indications of exudation at high relativehumidity, which is unsatisfactory.

IV Packaging and Handling A. Nitrogen Flex Test

To determine the ability of a bone dry film to be handled immediatelyafter issuing from a melt extruder without breakage, cast film stripsapproximately 2.54 cm.×10.2 cm., are hung overnight at 25° C. in a drybox purged with nitrogen. The strips are then creased in the shortdirection twice along the same fold. If no shattering or cracks result,the film is considered satisfactory.

B. Heat Sealability

The ability of a film (equilibrated≧2 hours at 27-70% relative humidity)to be formed into packages on an automatic packaging machine is judgedusing a Sentinel Pacemaker Impulse Heat Sealer (Model 12 TP, PackagingIndustries, Hyannis, Massachusetts). The movable upper jaw is equippedwith a 0.32 cm. nichrome ribbon. Both the upper and the bottom jaws arecovered with Teflon®-impregnated glass fabric.

A doubled 2.54 cm.×10.2 cm. strip of film of 1-2 mil thickness is heatsealed at 2.11 kilograms/cm.² with an impulse time of one second orless. If the film does not burn through and tears upon attempting topull open the seal, the film is satisfactory.

C. Package Drop Test

This test simulates the behavior of an 8 ounce package during storageand rough handling in shipment.

Lead shot (3.36 mm. diameter, 45 grams) is heat sealed in a packet (5.08cm.×5.08 cm. layflat) formed from water-soluble film (1.5-2.0 mils). Thepacket is equilibrated at 50-70% RH (≧5 hours) and then heat sealed in amoistureproof overwrap of 3.5 mil laminate composed ofpolyethylene/aluminum foil/polyethylene/Kraft paper. The overwrappedpackage is equilibrated at 0° C. (≧15 hours) and then quickly dropped1.22 meters onto a tile floor. Water-soluble packets which remain intactpass the test.

V. Auxiliary Packaging Tests A. Tensile Properties

Tensile properties and percent elongation are measured on 2.54 cm.×5.08cm. strips of film using an Instron with a cross head speed of 5.08cm./minute.

B. Stress Flex

Resistance to flexing under stress is determined by conditioning for 24hours at a given relative humidity a 10.2 cm.×17.8 cm. film to betested. Strips which are 2.54 cm. wide are clamped along each of the17.8 cm. edges between two parallel rubber-faced jaws, 1.27 cm. apart,and in the same plane. The 5.08 cm. width of unclamped film forms a "U"shape between the jaws. The assembly is arranged to rotate the commonplane of the jaws at 60 RPM around a center line lying in the plane inthe 10.2 cm. direction of the film, and passing through the center ofthe closed jaws. One jaw is fixed. The second jaw, weighing 681 grams,is arranged to slide freely maintaining parallelism with the 1.27 cm.spacing from the fixed jaw and restrained only by the film under test.Thus, each half revolution of the assembly, the movable jaw movesrelative to the fixed jaw, removing the slack from the film specimenbeing tested, and producing a series of diagonal and parallel wrinklesin the film extending from jaw to jaw. When the plane of the jaws isvertical, a load of 681 grams is applied to the film under test. Thesliding jaw applies an initial shock load to the film each halfrevolution as it slides from one extreme position to the other. Eachhalf revolution is counted as one stress-flex cycle. The test isterminated when the film sample breaks, allowing the movable jaw tostrike a switch which interrupts the electrical power used to rotate theassembly.

C. Slip

Ease of slip of the extruded films over rigid surfaces, e.g., a formingcollar of a vertical make-and-fill packaging machine, is determined bymeasuring the kinetic coefficient of friction (C.O.F.) of the film. A5.08 cm. wide strip of film is placed on a platform driven at 15.2cm./second. A puck of known weight (200 grams) is placed on the film andattached to a force gauge. The dynamic average force is noted. TheC.O.F. is the force value divided by the puck weight; C.O.F. value≦0.3are satisfactory. (Coefficient of Friction Tester D-1005, Kayeness,Inc., Downingtown, Pa.)

EXAMPLE 1 POWDERY FEED PREPARATION FOR MELT EXTRUSION

204 Kilograms of a suitable polyvinyl alcohol is charged to a 566 literribbon blender. The desired quantity of a suitable polyethylene glycol,neat or as an aqueous solution, is sprayed therein over a period ofabout 1 to 11/2 hours. The inclusion of 5-10 parts by weight of waterper 100 parts of polyvinyl alcohol gives a more free flowingcomposition.

EXAMPLE 2 FLAT DIE; SINGLE SCREW EXTRUSION

Two powdery feeds are prepared as in Example 1 according to thefollowing compositions:

(a)

0, 5, and 10 parts by weight water

10 parts by weight Carbowax® 400

100 parts by weight Elvanol® 51-05

(b)

10 parts by weight water

15 parts by weight Carbowax® 400

100 parts by weight Gohsenol® GL-05 (Nippon Gohsei, see PolyvinylAlcohol, Finch, pp. 18-21, 1973, John Wiley & Sons)

and are fed into a Wayne 1.91 cm. single screw extruder equipped with acoathanger flat die having a 5.08 cm. flat slit with a 30 mil gap.Tempertures along the barrel vary from 170°-240° C. (pressure 35.2-70.4kilograms/cm²) while film is successfully extruded. The extruded filmsare clean, glossy, nearly colorless, and nearly gel free. No bubbles orexudation are observed. The films are easily drawn down (stretched) to 1mil thickness by a moving belt.

The films so produced easily pass all of the above-described StandardTests. The tensile properties of the films when equilibrated and testedat the indicated relative humidities are given in the following table:

                  TABLE 1                                                         ______________________________________                                               %                                                                      Comp.- relative          tensile                                                                              yield %                                       sition humidity modulus* strength*                                                                            point*                                                                              elongation                              ______________________________________                                        (a)    35       54       2.9    2.0   170                                     (a)    50       22       2.1    2.1   310                                     (b)    35       76       3.1    1.8   230                                     (b)    50       21       2.4    2.5   385                                     ______________________________________                                         *in kilograms/mm                                                         

EXAMPLE 3 TWIN SCREW EXTRUSION OR POWDERY FEED

Various powdery feeds are prepared as in Example 1, the compositions ofwhich are summarized in Table 2 below. The feeds are fed into a twinscrew melt extruder (Packaging Industries, Inc., Hyannis, Mass.) with aL/D=16:1, a vent in the center and a 66 cm. flat die slit with a 5 milgap. At 175°-200° C. a colorless, clear, nonexuded film is threadedaround chrome-plated driven quench rolls (at room temperature or watercooled), is nipped between rubber rollers and drawn to variousthicknesses (0.5-3 mil) by varying the extrusion and windup rates.Extrusion rates of about 27 kilograms per hour (equal to the capacity ofthe extruder) are achieved with a screw speed of 55 RPM, a wind-up rateof 42.7 meters/min., and thicknesses of 0.5-1.5 mil.

The films so produced easily pass Standard Tests I, II, III, and IV. Theproperties of the films when equilibrated and tested at the indicatedrelative humidities are given in the following table:

                                      TABLE 2                                     __________________________________________________________________________    TWIN SCREW EXTRUDED FLAT DIE FILM                                             Film                                                                          Composition                                                                           MD/TD.sup.6                                                                                               Slip                                                                              Film Spray                                                                Coeffi-                                                                           Disc Tank                                 PBW Rela-                  No. of                                                                             cient                                                                             Water                                                                              Cold                             100 Carbo-                                                                            tive              %    Stress                                                                             of  Solubil-                                                                           Water Solu-                      PBW wax®                                                                          Humid-   Tensile.sup.5                                                                      Yield.sup.5                                                                       Elon-                                                                              Flex Fric-                                                                             ity  bility                           PVA 400 ity %                                                                             Modulus.sup.5                                                                      Strength                                                                           Point                                                                             gation                                                                             Cycles                                                                             tion                                                                              (minutes)                                                                          (minutes)                        __________________________________________________________________________    GL-05                                                                             10  20                     95/34                                          51-05                                                                             15  20                     180/57                                         GL-05                                                                             10  35                     162/182                                                                            0.30.sup.1                                51-05                                                                             15  35                     249/288                                                                            0.28.sup.1                                GL-05                                                                             10  50  13/17                                                                              2.4/2.4                                                                            2.4/2.4                                                                           283/384                                             51-05                                                                             10  50  12/12                                                                              2.2/2.2                                                                            2.2/2.2                                                                           246/271                                             GL-05                                                                             15  50  8.4/7.0                                                                            1.9/1.9                                                                            1.9/1.9                                                                           260/259       0.3-Drop.sup.2                                                                     0.6-Break.sup.3                  51-05                                                                             15  50  9.2/9.8                                                                            2.0/2.2                                                                            2.0/2.2                                                                           278/322       0.3/mil-                                                                           1.5-Released                     GL-05                                                                             10  65  9.8/10                                                                             2.1/1.5                                                                            1.0/1.0                                                                           243/214   0.25.sup.4                                                                        Complete                                                                           5Complete                        51-05                                                                             15  65  5.1/4.6                                                                            1.3/1.2                                                                            0.8/0.8                                                                           213/218   0.26.sup.4                                __________________________________________________________________________     1. Machined metal to film slip                                                2. Film equilibrated with a relative humidity =58%; film thickness =2 mil     3. Film equilibrated with a relative humidity =58%; film thickness =1.5       1.7 mils; pillow pack =21.6 cm. ×16.5 cm. and contained 454 grams       Lannate®90WD                                                              4. Puck covered with Teflon®-impregnated glass cloth tape                 5. Kilograms/per square millimeter                                            6. Machine Direction/Transverse Direction                                

EXAMPLE 4 SIMULATED FILLED PACKAGE HANDLING

Two pillow packs 1.5-1.8 mils thick, 43.2 cm. and 16.5 cm. wide are madeby heat sealing extruded films based on 100 parts Elvanol® 51-05 andbased on Gohsenol® GL-05 with 15 parts and 10 parts of Carbowax® 400,respectively. The packs are each filled with five pounds of granulatedsugar, sealed, and equilibrated overnight at 45% relative humidity. Theyare each then dropped onto a tile floor from heights of first 91.4 cm.and then 183 cm. successively without leakage or apparent damage.

A 38.8 cm.×38.1 cm. heat sealed pillow pack, made from 100 partsElvanol® 51-05/15 parts Carbowax® 400, 1.5 mils thick, containing 4.54kilograms of granulated sugar is placed in a 11.3 liters fiber pack anddropped 91.4 cm. to the floor with no breakage. The entire intact filmpackage can be conveniently delivered to a spray tank upon up-ending thecarton.

Pillow packs containing 227 grams and 908 grams of Lannate® 90WD areproduced on an automatic vertical make-and-fill packaging machine usingblown film based on 51-05 and on GL-05, each containing 15 pbw ofCarbowax® 400. The machine is operated with intermittant motion andeffects vertical seals by a constantly heated bar and horizontal sealsby impulse with a nichrome ribbon. Production speeds of 15-30 packagesper minute are demonstrated.

    ______________________________________                                                            Pillow pack                                                                   dimensions                                                                    (cm.)                                                     Package size                                                                              film gauge               layflat                                  (pounds)    (mils)        height     width                                    ______________________________________                                        227 grams   1.2-1.5       14-15.2    16.3                                     908 grams   1.5-2.1       30.5       17.3                                     ______________________________________                                    

The 908 grams and 227 grams pillow packs are equilibrated to 50%relative humidity, overwrapped (as per IV (C), and cooled to 10° C. and0° C., respectively. Both packages survive 122 cm. drops. The sameresults occur when the overwrapped packages are packed in cardboardcartons (5.45 kilograms per carton), cooled, and the cartons dropped(122 cm.) once on the bottom and once on each of two sides.

EXAMPLE 5 FILLED PACKAGE STORAGE AND SPRAYING

Duplicate pillow packs (6.35 cm. high×7.62 cm. wide) are made frommelt-extruded film approximately 1.5 mils thick of 100 parts Elvanol®51-05/15 parts Carbowax® 400, and are each filled with 10 grams of oneof several pesticides (Lannate® 90WD Methomyl Insecticide, Lorox® 50WPLinuron Weed Killer, Manzate® D Maneb Fungicide, Benlate® BenomylFungicide, Hyvar® X Bromacil Weed Killer, Tupersan® 50 Siduron WeedKiller, Marlate® 50 Methoxychlor Insecticide, and Thylate® ThiramFungicide), and placed in moistureproof overwrap envelopes comprised ofa polyethylene/aluminum foil/Kraft paper laminate. The envelope is heatsealed and then placed in an oven and maintained at 45° C. for 21 days,thus simulating approximately one year of pesticide storage. Chemicalanalysis indicates no change in the level of active ingredient duringstorage. All of the packages are removed from the envelopes easily andpass the spray test. The same results are obtained for pillow packs ofLannate® stored 16 months at room temperature.

Three of the spray tank solutions (Lannate®, Benlate®, and Manzate®) aretested for biological activity and are found to be as active as controlsolutions of these pesticides.

EXAMPLE 6 COMMERCIAL SCALE BLOWN FILM EXTRUSION

Ribbon blends of each of the following compositions are prepared as inExample 1:

(a)

100 parts Gohsenol® GL-05 (containing 0 and 5 parts water)

15 parts Carbowax® 400

(b)

100 parts Gohsenol® GL-05 (containing 0 and 5 parts water)

20 parts Carbowax® 400

(c)

100 parts Gohsenol® GL-05 (containing 0 and 5 parts water)

15 parts Carbowax® 400

2 parts polyethylene oxide (Polyox® WRPA 3154, Union Carbide, 900,000average molecular weight)

Each composition is fed into the twin screw extruder (in Example 3) witha double-holed die about 0.64 cm. diameter. Clear, non-exuded rodding ismade and quenched with air knives, with preferred barrel-dietemperatures of 190°-210° C. (At melt temperatures of about 200° C.,very low pressures develop. Some of the composition (a) is extruded at130°-180° C.) The rods are cut into pellets, allowed to cool undernitrogen and fed into a 6.35 cm. Eagon melt extruder (Frank W. Eagon &Co.; Bound Brook, N.J.) with a single screw, of a type commonly used inthe extrusion of Alathon® polyethylene. The extruder is equipped with a25.4 cm. diameter annular die of 25 mil lip opening. The verticallyissuing molten tube is cooled by an air ring, inflated by air,collapsed, nipped, and conveyed to the windup section. Collapsed tubing0.5-5 mils thick, up to 91.4 cm. layflat width is produced at rates upto 54.5 kilograms per hour (about 13.7 meters per minute). In-lineslitting, delamination, and windup is performed over a range of about30-65% relative humidity. The following table summarizes the operatingconditions for each of the three compositions.

                  TABLE 3                                                         ______________________________________                                                   barrel die   melt       pressure                                              temperature  temperature                                                                              kilograms/                                 Composition                                                                              °C.   °C. mm.sup.2                                   ______________________________________                                        (a)        185-205      200-210    2.4                                        (b)        165-185      185        1.4                                        (c)        193-200      200        2.1                                        ______________________________________                                    

The resulting films are essentially colorless, non-exuded, non-voided,and contain few gels. Films (a) and (b) are clear. Film (c) is slightlyhazy. Film (c) exhibits less tackiness and better slip at high relativehumidity, and excellent low temperature (-15° C.) flex. Film propertiesare given in Table 4.

                                      TABLE 4                                     __________________________________________________________________________    BLOWN FILM                                                                                                                Film Spray                                MD/TD                               Disc Tank                                 Rela-                  No. of       Cold Cold                         Film    tive              %    Stress       Water                                                                              Water                        Compo-  Humid-   Tensile                                                                            Yield                                                                             Elon-                                                                              Flex Elmendorf                                                                             Solu-                                                                              Solu-  Package               sition  ity %                                                                             Modulus.sup.1                                                                      Strength.sup.1                                                                     Point.sup.1                                                                       gation                                                                             Cycles                                                                             Tear.sup.2                                                                            bility.sup.3                                                                       bility.sup.3                                                                         Drop                  __________________________________________________________________________    (a)     20                     216/125                                                35  158/134                                                                            12/8.4   212/232                                                                            332/346                                                                            38/1190      0.3 break                                                                     1.0 release                                                                   <3 complete.sup.4            50       11/13                                                                            3.3/2.1                                                                            145/180            0.1 drop.sup.4                                                                             pass 0° C.                                                        0.8 min./                                 62                                  mil                                                                                       pass-6°                                                                C.                    (b)     31                                  0.1 drop.sup.5                                                                0.8 min./                                                                     mil                               (c)     20                     116/94                                                 35  137/177                                                                            12/6.3   198/166                                                                            331/301                                                                            42/468                                            50   11/11                                                                             2.8/2.1                                                                            2.8/2.1                                                                           212/220                                             __________________________________________________________________________     1. in kilograms per square millimeter.                                        2. in grams per mil; ASTM Method D 192261t 1964 Standards, Part 27, p642      3. minutes                                                                    4. 1.4 mils                                                                   5. 1.3 mils                                                              

Table 4 demonstrates that stretch during melt extrusion and windupprovides orientation which greatly increases tear strength (compare,e.g., for (a) the 30-fold increase in tear strength for TD vs. MD)--anadvantage not obtained via simple solvent casting. The orientationprovides other toughness advantages. For example, a filled packagecomprised of an aqueous cast film (51-05/100 and Carbowax® 400/15 pbw)was found to fail in the Package Drop Test (0° C., 50% relativehumidity).

All of these films pass all of the standard tests and exhibit Film DiscCold Water Solubility of 0.5-0.8 min./mil. A pillow pack of film (a)containing 227 grams of Lannate® breaks at 0.3 minutes, releases at oneminute, and dissolves completely in less than 3 minutes in the SprayTank Test. Similar results were obtained when the blown film extrusionwas repeated using Elvanol® 51-05 in place of Gohsenol® GL-05 with 15pbw of Carbowax® 400.

EXAMPLE 7

Polyethylene glycol, having an average molecular weight of 330, andGelvatol® 20-30 brand of polyvinyl alcohol were used to prepare anaqueous cast film by the procedure given in Stardard Test I. Theresulting film (comprised of 100 pbw PVA and 15 pbw of PEG 330) wasexamined using Standard Tests I through IV, to give the results shown inTable 5.

                                      TABLE 5                                     __________________________________________________________________________    STANDARD TESTS                                                                I      II                        III          IV                                     -A          -B                                                         film   break                                                                             release                                                                           dump                                                                              drop                                                                              total                                                                             dissoln.   preheat                                                                           extrud-                             gauge  time                                                                              time                                                                              time                                                                              time                                                                              time                                                                              rate  physical                                                                           time                                                                              ability                             (mils  (min.)                                                                            (min.)                                                                            (min.)                                                                            (min.)                                                                            (min.)                                                                            (min./mil)                                                                          form (min.)                                                                            index                                                                             -A -B -                         __________________________________________________________________________    1.5 pass                                                                             0.3 0.7 5.0 0.6 1.3 0.9   aqueous                                                                            7   14  pass                                                                             pass                                                                             pass                                                       cast                                                                          film                                                                          trace                                                                         of fog                                                                        on plate                                     __________________________________________________________________________

Table 5 shows that the film passed all the stardard tests with theexception of a marginal pass in the exudation portion of Test III; i.e.a trace of plasticizer exudation was indicated. That this result isinsignificant is shown in the following small scale extrusion using ablend having the same basic ratio of PVA/PEG as above.

A powdery blend was made using the components below by spraying aqueousPEG into the PVA powder, while tumbling in a one-gallon jar:

                  TABLE 6                                                         ______________________________________                                        BLEND COMPOSITION                                                             Gelvatol®20-30                                                                             PEG 330   WATER                                              ______________________________________                                        533 g.           80 g.     16 g.                                              ______________________________________                                    

The above blend was fed to a Killion single screw extruder equipped witha one-inch diameter sudden compression Alathon® type screw (KillionExtruders, Inc., Verona, N.J., L/D 21) and a single hole (3/16-inchdiameter) die. Using the conditions below, a clear, light amber rod wassuccessfully extruded onto a conveyer belt and then cut to pelletsin-line with the extrusion. The rod occasionally was foamed because ofsteam venting through the die rather than through the feed throat. Noexudation was observed on the die, rod, or take-off belt at any timeduring the extrusion.

                  TABLE 7                                                         ______________________________________                                                                         Melt                                         Screw     Pressure Barrel-die    Temperature                                  RPM   Amps    (p.s.i.) temperatures (°C.)                                                                 (°C.)                               ______________________________________                                        23    4.0     low      160-180     205                                        ______________________________________                                    

These melt extrusion pelletizing tests demonstrate that PEG 330/PVA isan acceptable composition for the preparation of useful melt-extruded,cold water-soluble film.

EXAMPLE 8

Polyethylene glycol, having an average molecular weight of 533, andGelvatol® 20-30 brand of polyvinyl alcohol were used to prepare anaqueous cast film by the procedure given in Standard Test I. Theresulting film (comprised of 100 pbw of PVA and 15 pbw of PEG 533) wasexamined using Standard Tests I through IV to give the results shown inTable 8 (the film passed all of the standard tests).

                                      TABLE 8                                     __________________________________________________________________________    STANDARD TESTS                                                                I      II                        III          IV                                     -A          -B                                                         film   break                                                                             release                                                                           dump                                                                              drop                                                                              total                                                                             dissoln.   preheat                                                                           extrud-                             gauge  time                                                                              time                                                                              time                                                                              time                                                                              time                                                                              rate  physical                                                                           time                                                                              ability                             (mils) (min.)                                                                            (min.)                                                                            (min.)                                                                            (min.)                                                                            (min.)                                                                            (min./mil)                                                                          form (min.)                                                                            index                                                                             -A -B -C                        __________________________________________________________________________    1.5 pass                                                                             0.4 1.0 6.1 0.6 1.2 0.8   aqueous                                                                            7   10  pass                                                                             pass                                                                             pass                                                       cast                                                                          film                                                                          no fog                                                                        on plate                                     __________________________________________________________________________

These tests demonstrate that PEG 533/PVA is an acceptable compositionfor the preparation of useful melt-extruded, cold water-soluble film.

EXAMPLE 9 Extruded Films with Slip Addittives A. Twin Screw Blown Film

Powdery blends (see Table 9) were prepared in a 3 cu. ft. ribbon blenderusing the procedure of Example 1, except the slip agents were added tothe PVA and tumbled with it initially. These blends were fed to theextruder of Example 3 equipped with a vent port (under partial vacuum)and a two hole die (1/8" diameter holes). The extrusion conditions aregiven in Table 10.

                  TABLE 9                                                         ______________________________________                                                            Slip Agents                                               Blend                                                                         No.   PVA.sup.1                                                                             Carbowax®400                                                                          Water Identity pbw                                  ______________________________________                                        1     100     15          5     XL-223.sup.2                                                                           0.5                                  2     100     15          5     Carbowax®                                                                          1                                                                    4,000.sup.3                                   3     100     15          5     cabosil M-5                                                                            1                                    4     100     15          5     Magnesium                                                                              0.5                                                                  Stearate.sup.4                                5     100     15          5     Sodium   0.5                                                                  silicate.sup.5                                6     100     15          5     Polysili-                                                                              1                                                                    cate®85                                   ______________________________________                                         .sup.1 Elvanol®51-05G by Du Pont                                          .sup.2 partially oxidized low molecular weight polyethylene of American       Hoechst                                                                       .sup.3 average molecular weight in the range of 3,000 to 37,000               .sup.4 Fisher Lab Grade                                                       .sup.5 Fisher Technical Grade                                            

                  TABLE 10                                                        ______________________________________                                        Pelletizing Extrusion                                                         Temperatures (° C.)                                                    Blend          Die           (psi)                                            No.   Barrel   Adapter  Melt Pressure                                                                             RPM   lb/hr.                              ______________________________________                                        1     195-210  185      196  125    19    15                                  2     189-209  182      219  300    14    14                                  3     198-210  182      201   50    19    11                                  4     198-210  187      204   50    18     9                                  5     187-208  181      217  250    14    15                                  6     190-210  180      --   200    14    --                                  7     196-210  187      198   25    18     9                                  ______________________________________                                    

The rods were conveyed by a conveyer belt, quenched by air knives, andchopped to pellets in-line with the extrusion. The same extruder wasthen fitted with a 3-7/8 inch diameter circular die (vent of extruderclosed) and a screen pack (20/40/60/80/20 mesh), and collapsed tubing(1-3 mils thick, 13-17 inches layflat width) was prepared from the abovepellets in accordance with the prodedure of Example 6, using theconditions set forth in Table 11.

                  TABLE 11                                                        ______________________________________                                        Blown Film Extrusion                                                          Temperatures (° C.)                                                    Blend            Die            (psi)                                         No.    Barrel    Adapter   Melt Pressure                                                                              RPM                                   ______________________________________                                        1      183-199   170-181   205  3800    20                                    2      198-215   196-205   208  2600     9                                    3      190-205   178-190   210  3000    19                                    4      199-203   180-188   216  3700    22                                    5      194-209   160-195   199  2200    10                                    6      190-215   160-200   193  --      11                                    7      195-200   171-188   200   500    17                                    ______________________________________                                    

All of the films passed all the standard tests and had improvedfilm-metal slip at 50% relative humidity as measured by Auxillary TestV-C. In addition, Blend 4 film had excellent film-film slip.

B. Commercial Scale Single Screw Blown Film 1. Pelletizing withPlasticizer Injection

The extruder used was a 53 mm twin screw extruder by Werner & PfleidererCorporation, Waldwick, N.J. (machine type ZSK 53 L) equipped with fivebarrel sections. PVA and the slip agent(s), as powdery solids, weredelivered by solids feeders to the feed throat. As a polymeric melt wasachieved, Carbowax® 400 was injected into the first barrel section.Steam was vented from ports in the last two barrel sections, and tenrods (3/16" diameter) emerged from a straight take-off die onto aconveyor belt. The rods were cooled by air knives and a water cooledmetal surface, and chopped to pellets in-line with the extrusion. Thepellet composition and pelletizing extrusion conditions are given inTable 12.

This is a preferred pelletizing procedure, since dry pellets may beproduced at a high rate, and the preblending step of plasticizer and PVAis eliminated. This procedure possesses an additional advantage, in thatit avoids holes and craters encountered during film extrusion from wetpellets.

                                      TABLE 12                                    __________________________________________________________________________                                   Measured                                              Composition (pbw)       Temperature (° C.)                      Composition        Zeolex®                                                                        Magnesium.sup.2                                                                           Die            (psi)                                                                              Pellet                No.    PVA.sup.1                                                                         Carbowax®400                                                                      23-A stearate                                                                             Barrel                                                                             Adapter                                                                            % Torque                                                                            RPM Pressure                                                                           Rate                  __________________________________________________________________________                                                            (lbs./hr)             1      100    15.6 1    --     178-210                                                                            190  91    270 40-75                                                                              164                   2      100 14.9-15.6                                                                             1    0.1    175-230                                                                            195-199                                                                            90    270 30   163                   __________________________________________________________________________     .sup.1 Gelvatol®20-30                                                     .sup.2 U.S.P. grade by Nopco Division of Diamond Shamrock                

2. Single Screw Blown Film Extrusion

The above pellets were fed to an MPM 3.5 inch (L/D=20) single-screwextruder by Modern Plastics Machinery. The extruder was equipped with a60/30 mesh screen pack and a 3 inch diameter annular die (25 mils gap).Collapsed tubing (18 inches layflat width comprised of film 1.5-2 milsthick) was produced and wound in-line in accordance with the procedureof Example 6, using the conditions of Table 13.

                                      TABLE 13                                    __________________________________________________________________________           Measured Temperature (° C.)                                     Composition Die       %      Pressure                                                                           Film Rate                                   No.    Barrel                                                                             Adapter                                                                            Melt Load                                                                             RPM (psi)                                                                              (lbs/hr.)                                   __________________________________________________________________________    1      160-204                                                                            168-191                                                                             191 38 26  3400 84                                          2      163-204                                                                            168-191                                                                            191-193                                                                            38 26  3400 84                                          __________________________________________________________________________

These films had exceptional gel-free, wrinkle-free, and smooth surfacesand passed all standard tests. They exhibited excellent packagability ona vertical-form-fill-and-seal packaging machine; the films exhibitedexcellent slip over the forming collar and forming tube, even at highhumidities.

What is claimed is:
 1. A composition suitable for use in the preparationof melt-extrudable, cold water-soluble films consisting essentially of 5to 20 parts by weight of a polyethylene glycol, having an averagemolecular weight in the range between 325 and 550 (based uponmeasurement of the hydroxyl content thereof obtained by esterificationof said glycol with phthalic anhydride/pyridine), in 100 parts by weightof a low molecular weight polyvinyl alcohol which is about 85 to about90 mol% hydrolyzed (determined by saponification) and has a viscosity inthe range between about 3 and about 10 cps as measured on a 4% aqueoussolution at 20° C. (determined by the Hoeppler Falling Ball MethodASTM-D 1343-56, Part 8).
 2. The composition of claim 1 wherein saidpolyethylene glycol is present in an amount in the range between about12 and about 17 parts per 100 parts by weight of said polyvinyl alcohol.3. The composition of claim 2 wherein about 15 parts of saidpolyethylene glycol per 100 parts by weight of said polyvinyl alcoholare present.
 4. The composition of claim 1 wherein said polyvinylalcohol has a viscosity between about 4 and about 6 cps.
 5. Thecomposition of claim 1 wherein said polyethylene glycol has an averagemolecular weight between about 380 and about
 420. 6. The composition ofclaim 5 wherein said polyethylene glycol is present in an amount of12-17 parts by weight per 100 parts of said polyvinyl alcohol.
 7. Thecomposition of claim 6 wherein the viscosity of said polyvinyl alcoholis between about 4 and about 6 cps.
 8. The composition of claim 6wherein said polyethylene glycol is present in an amount of about 15parts by weight per 100 parts of said polyvinyl alcohol.
 9. Thecomposition of claim 8 wherein the viscosity of said polyvinyl alcoholis between about 4 and about 6 cps.
 10. The composition of claim 1containing 2 parts or less by weight per 100 parts of polyvinyl alcoholof a water-soluble polymer, said polymer being selected from polyethersof the formula --[CH₂ CH₂ O]_(n) -- with a molecular weight of at least600 which are sometimes referred to as polyethylene glycols andsometimes as polyethylene oxides, polypropylene glycol having an averagemolecular weight of at least 400, and ethylene oxide/propylene oxidecopolymers having an average molecular weight of at least
 400. 11. Thecomposition of claim 10 wherein said polymer is a polyethylene oxidewith average molecular weight between about 500,000 and about 1,000,000.12. The composition of claim 1 containing 5 parts or less by weight ofan adjuvant per 100 parts by weight of said polyvinyl alcohol, saidadjuvant being selected from antioxidants, release agents, anti-blockagents, slip agents and fillers.
 13. The composition of claim 12 whereinthe amount of said adjuvant comprises 0.1 to 2 parts by weight per 100parts by weight of said polyvinyl alcohol.
 14. The composition of claim12 wherein said adjuvant is a slip agent.
 15. The composition of claim14 wherein said slip agent is selected from calcium stearate, magnesiumstearate, hydrated sodium silico-aluminate, and mixtures thereof. 16.The composition of claim 15 wherein said slip agent is a mixture ofmagnesium stearate and hydrated sodium silico-aluminate.